Telephone-exchange system



Dec. 19, 1922. 1,439,213.

r S. B. WILLIAMS, JR.

TELEPHONE EXCHANGE SYSTEM. I

FILED APR. 24. I919- SHEETS-SHEET 2.

Af/y.

s. B. WILLIAMS, JR.

Dec. 19,1922. 1,439,213;

TELEPHONE EXCHANGE SYSTEM.

FILED APR- 24, 1919- Q 4 SHEE'[SSHEET 3- I five/flan Samue/ 5 [MW/M77511:

Dec. 19, 1922..

s. B. W|L|.|AMS,1R. TELEPHONE EXCHANGE SYSTEM.

4 SHEETS-SHEET 4- EILEH APR. 24, 1919 //?ve./1fa Samue/ 6f Wf/Mams J7:

' wry Patented Dec. 19, 1922.

entree. stars raiser eerie.

SAMUEL B. WILLIAMS, 5a., or BROOKLYN, new YORK, ASSIGNOE TO wnsrnan ELEC- rnro COMPANY, rnconronernn, or NEW roan, 1v. Y. v

riiLnrnonn-nrrorranen svsrmu.

Applicationfiled April 24, 1919. Serial No. 292,254.

1 0 all whom it may concern Be it known that T, SAMUEL B. WILLIAMS, J12, a citizen of the United States, residing at Brooklyn, in the county of Kings, State oit' New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to improvements in telephone exchange systems and has particular reference to a switching arrangement therefor. I

An object of the invention is to provide an improved interconnecting means for telephone lines which will have the advantage of certain so-called relay systems and, at the same time, may be operated in the manner of and in accordance with the present day full automatic practice.

Heretotore such relay systems have either required the extension of large numbers of conductors to each subscribers line orhave required such systems to be operated in a peculiar manner or in a manner different from the present day standard automatic practice.

Another object of arrange the circuits that the system may cooperate with present day standard telephone systems and involve no new methods of operating therein.

A "further object is to produce a novel impulse controlling mechanism tor controlling the subscribers line interconnecting means which may be actuated through the operationsordinarily performed at an automatic telephone substation.

A still further object is to reduce to a minimum the necessary interconnecting apparatus and to thereby simplify, cheapen and make more efficient such a system; 1

An additional object is to reduce the amount of apparatus necessary by making as much of it as possible common to all subscribers and to provide only as much OfSllCll common apparatus as trati'ic conditions will allow.

in carrying out the above objects, the various connections made in establishing a call between two subscribers lines or between a subscribers line and a central ofiice trunk are preferably controlled by relays. The control of the relays is responsive'to the variable operations of a common set of the invention is to so' The inventive idea involved is capable of receiving a variety of expressions one of which, for the purpose of illustrating the invention, is shown in the accompanying drawings, but it is to be expressly under stood that said drawings are employed only for the purpose of facilitating the description of the invention as a whole and not to define the limits thereof, reference being bad Y to the appended claims forthis purpose.

In the drawings Figs. 1, 2, 3 and 5 with Fig. 2 arranged beneath Fig.1, Fig, 3 to the left of Fig. 2, and Fig-5 beneath Fig. 3, illustrate diagrammatically the-circuits employed in carrying out'the invention. Fig.

4 is a tabulation of an impulse translating code used in connection with the impulse controlling mechanism.

Briefly, the invention is shown as used in connectionwith a private branch exchange system. The subscribers lines within the exchange are arranged to-have access to any one of a plurality of outgoing linlr circuits, the number oi such circuits being lessthan the number of the subscribers lines.

Two outgoing link circuits are shown in Fig. 2, although it will-be understood that as many circuits may be employed as is found necessary to adequately handle the particular traliic conditions encountered. Each outgoing link circuit has permanently paired or associated therewith an incon'iing link circuit for completing'a loop circuit from a calling to a called subscribers line. Upon the automatic" selection of any one of the outgoing link circuits, when a call is initiated, the subscribers line is extended, by

the energization of a relay at the point of junction of said line with said outgoing link circuit, to a mechanism shown at the right of ,Fig. 3 which is individual to, the outgoing and incoming link circuits selected. An idle impulse controlling mechanism shown in Fig. 5 and common to a plurality of'linlr circuits is then selected through junction relays shown at'the lett of said figure. In response to sets of impulses transmitted. from the calling subscribers substation, certain counting relays of said controlling mechanism are operated in accordance with a suitable code shown in Fig. 4. Through the operation of a particular counting relay actuated, when the first set of impulses is transmitted, a certain translating relay or relays, illustrated at the left of Fig. 3, are energized to select one of a group of relays corresponding to the first digit of the called line. Enclosed by the dotted lines at the left of Fig. 3 are a plurality of groups of switching devices or relays individual tothe seized link circuits, the relays of each group being individual to a subscribers line. The selection of any one of the group of relays corresponding to the first digit of the called line determines in which of the groups the particular relay individual to the wanted line is lo cated. The last set of impulses transmitted through the impulse controlling mechanism then determines the relay in, the selected group which is individual to the Wanted line, whereupon the desired connection is established.

Provision is also made for establishing a connection from a subscrib ers substation within the exchange to a trunk leading to a central oflice exchange. In this instance, an outgoing link circuit is seized by the calling subscriber in the same manner as previously referred to, with a result that the apparatus individual to said link circuit and an impulse controlling mechanism common to a number of link circuits, are also engaged for use. Only one set of impulses is required to establish a connection to a central office trunk, and the transmission of this set of impulses will operate one of the counting relays of the controlling mechanism to establish a certain electrical condition. This electrical condition is conveyed to the group of translating devices or relays which again coordinate to actuate another relay common to the central ofiice trunks. In response to the actuation of this latter relay, an idle central office trunk is seized and the next idle trunk simultaneously preselected to handle another call.

In establishing a call from a central. oflice exchange to a subscriber within the private branch exchange, a connection is first set up automatically from the central office opcrators "position to one of a plurality of receiving stations in the private branch ex change which is automatically preselected. These receiving stations are of the same nature as a subscribers substation and upon the selection of one of them, the attendant thereat, in responseto information conveyed by the central ofiice operator, may dial for the wanted subscriber in the same manner as referred to in connection with the establishment of a call between subscribers within the exchange.

It is believed that the invention will now be fully understood from the following de tailed description of the operation in establishing the various connections. Let it first be assumedthat a subscriber at substation A desires to establish a connection with another subscriber within the private branch exchange. Upon removal of the receiver from its switchhook at substation A, a circuit is closed for relay 100 extending from grounded battery, winding of said relay, back contact and outer armature of cutoff relay 10.1, substation apparatus, inner armature and back contact of relay 101 to ground. Relay 100 energizes and closes a circuit at its left-hand armature for relay 102 extending from grounded battery, winding of relay 102, front contact and left armature of relay 100 to ground. Assuming that the first outgoing link circuit is idle, energization of relay 100 closes a circuit extending from ground, right armature and contact of relay 100, right armature and back contact of relay 302 individual to said link circuit and winding of relay 200 to grounded battery. The ground from the right-hand contact of relay 100 is also extended through the righthand contact of relays 302 of all other link circuits to energize relays similar to relay 200, but the energization of these other relays 200 has no effect as will presently appear. Relay 200 of the link circuit above mentioned becomes energized and closes a circuit for junction relay 201, extending from grounded battery, outermost armature and front contact of relay 102, winding of relay 201, front contact and middle armature of relay 200 to ground. In the same manner, junction relays similar to relay 201, such as relay 203, will also energize if their associated relays 200 are operated. Relay 201 of the first idle link energizes in the above circuit and closes a circuit for line relay 300 extending from grounded battery, right Winding of relay 300, back contact and inner left armature of relay 801, middle left armature and front contact of relay 201, substation apparatus A, front ntact and outer left armature of relay 201, outer left armature and back contact of relay 301, and left winding of relay'300 to ground. Energization of relay 300 closes a circuit for slow-to-release relay 303 extending from grounded battery, winding of said relay, front contact and armature of relay 300 to ground. Upon attracting its right armature, relay 303 closes a locking circuit for junction relay 201, extending from grounded battery,:winding of cutofi' relay 101. inner left armature and front contact of relay 201. winding of said relay, front contact and right armature of relay 201, the back contacts and right armatures of all other junction' relays associated with the outgoing circuit employed-including the last relay 202, Winding of relay 302 rightarmature and front contact ofrela'y 303 to ground. It

. will here be apparent that by the opening of the inner left-hand armature and back contact of relay 201,when this 'relay operated,

the locking circuits for relays 203' and other similar relays will be permanently opened "so that these relays cannot'lock up after being energized. Relay 101 is energized in energized in the circuit just described, and

. at'its right armature breaks the circuit for will then release.

relay 200 whichthen releases; By the release of relay 100 and removal of ground from itsright-hand contact, other relays similar to relay 200 which might have" been energized, will be caused to release andromove ground from ,tlIB-WIHClIIIgS'Of relays 203 and other like relay s,so,that these relays Thus,--it will beseen that although several junction relays may be energized when a call is initiated only the relay associated with, the first idle link circuit encounteredwill remainenergized and the others will restore. When relay 302' energizes, a circuit is established for relay 304 extending from grounded battery, winding of said relay, back contact of inner armatureof relay 305, back contact and middle left armature of relay 306,front contact and left armature of relay 302, back contact and upper armature of relay'316 to ground. En-

ergization of relay'304 causes the selection of an idle impulse controlling mechanism, a number of which mechanisms are provided for the purpose of handling simultaneous calls. Assuming that the controlling mechanism shown in Figi5 is the first idleone,. encrgization of relay 304 establishes a Cll"? cuit' extending from grounded battery, winding of relay 500, upper armature and back contact of relay 503,.front contact and left armature of relay304 to ground. Re lays 500 of other idle mechanisms will also energize, but their operations have no effect will presently be pointed out. of th firstidle mechanism energizes and closes a circuit traceable from grounded. battery', inner right armature and front contact of relay 304, winding of junction relay 501. winding ofjunction relay .501" in series with relay 5015 front contact and middle lower armature of relay 500 to ground. He

[lays 501 and 501 energize and lock up over a circuit extending from grounded battery, outer right armature and baclrcontact of 301, outer armature and back contact" relay of relay 307, outermost left armature and Relay 500 contact and outer armatureof relay 305,

back contact and innermost left armature of relay 306, and right 'WlIlCllIlQ of relay 309 to grounded battery. "Relay 309 does not, however, energize but the dial tone Induced into the left winding thereof and then traverses the previously described cir-- cuitrfor relay 300 through the calling subscribers substation apparatus. This dial tone is furnished to the calling subscriber to indicate that the impulse controlling Relays .305 and 503 mechanism of '5 has been selected and 0 ready to receive impulses transmitted from the calling substation. Operation of relay 305breal s the circuit for relay 304 which thenreleases. Relay :503,'in' attracting its upper armature, opens the circuit for relay 500 which also releases. Returning now to the point in the operation where relay 304 isenergized to establish a circuit for relay' 5.00, if there are other impulse mechanisms j idle at this'time, relays 500 of suchmechanisin will also-be operated and the, junction relays similar to relays 501 and 501 will be energized'in the samemanner as described for the latter relays. lloweve'r, these other similar relays cannot lock upv for thereason that their locking circuits extend through the ri ht ari'nature andback contact of relay 501 w ich is at this time operated; Relays 503 of mechanisms other thanjthe lirstidle.

:one will therefore not operate as the circuits for-these relays must also pass through the right armature and back contact of relay 501. It therefore follows that when relay 304 "is released as above described, the re lays 5,00 of the otheriidle impulse mechanisms will deenergize and causethe release of junction relays similar to relays 501 and The subscriber atsubstation A ma now manipulate his impulse sending; 'dev' 103 y in accordance with the first digit of; the

wanted line,and in response to the impulses transnntted, armature of line relay 300 will i 'ibrate, but relay303 being slow to release will remain energized-during the sinissionof the set of impulses 'Uponthe first deenergization of relay 300, a circuit is closed for slow to-release relay 504 extending from grounded'battery, winding of said relay Windingof relay 505, front contact inner left armature ofrelay 501 front con- 1 ,asaa is tact and leftarmature of relay 303, liiaclt contact and armature of r layilt ll to ground. Relays 50a and 505 are energized in this circuitand at its left armature, relay 501 closes a circuit for slow-to-release relay 500 extending from grounded'battery, winding of relay 506, front coi'itact and left armature of relay 50% to round. Belay 506 looks up over a circuit extending from grounded battery, winding, right armature and front contact of relay 506, bacl; contact'and armature of relay 507, back contact and left arma ture of relay 508 to ground. Energization of relay 50% also closes a circuit for relay 509 extending from grounded battery, winding of relay back contact and left armature of relay'510, right armature and front contact of relay 504,, front contact and-lower armature of relay 503 to around, said relay 503 having become ener ized in the previously described locking;- circuit for relays 501 and 501;. Relay 509 looks up over a circuit extending from grounded battery, winding, armature and front contact of said relay,

winding of relay 510, front contact and lower armature of rel y 503 to ground. Relay 510 does not, however, energize in this circuit at. thistimaduc to a shunt circuit which extends from ground at the lower armature and. front contact of relay 503, front contact and right armature of relay 504:, left armature and back contact of relay 510, armature and front contact of relay 509, and winding of relay 510 back to ground at the lower armature and front contact of relay 508. Energization of pulsing relay 505 in response to the firstiinpulse transmitted establishes a circuit for counting relay 1 extending from ground,'fr01it contact and armature of relay 505, the right armatures and back contacts ofrelays 1 to 10 and winding" of counting relay 1 to grounded battery 1 is counting relay ener 1 locks up over a circuit extending from grounded battery, winding); of said relay, front contact and right armature thereof, winding of relay 1, back contact and left armature of relay 2, front contact and left armature of relay506 to around. Relay 1, however, does not become energized in this circuit due to a shunt extending' from ground at the armature of relay 505, through the baclrcontacts and right armatures of relays "1 to 10, front Contact and armature of rel; y f], windin of relay 1" the front contact and left armatu e of relay 506. Upon the release of relay 505 at the t rmination of the first in'lpulse, this shunt is removed and relay lthcn energizes, and at its right armature prepares a. circuit for relay 2 which energizes when relay 5 ,5 is operated in response to the second impulse. This energizing circuit for counting relay 2 would then extent, through the front contact and right armature of relay 1, and upon energication of said counting relay the samewould lock lip-through the wlnding of relay 2' to the locking; ground at the front contact and left left armature breaks the locking circuit for counting relay 1 which extends through the winding of relay 1 and said countlng relays 1 and 1 would therefore deene'rgize. This operation continues until the impulses cor responding to the first digit of'the wanted line have been transmitted and the last 'countmg relay to become energized remains locked up while all of the preceding counting relays deenergiz'e. I I

In order to reduce to a minimum the number of relays employed in selecting the desired line, the impulse controlling mechanism includes a translation system, the code for which is illustrated in Fig. 1. In explanation of this code it is pointed out that there are four conductors, 51.1., 512, 513 and 5141 associated with thecounting relays, said conductors being denoted at the top of Fig. 1 as 1, 2, 3- and a respectively. Ten impulses are numbered at the left of said figure, and it will be seen that one impulse will apply ground, designated by 0, tothe first conductor 511. Two impulses will apply ground to conductors 512, four impulses to conductors 511 and 512, and so on in different coinbinations, ten impulses being adapted to con nect groundto the three conductors 511, 512 and 514, r

At the termination. of the first set of impulses corresponding to the first or tens digit of the wanted line, relay 300 remains energized and causes the release of relay 505.

.At the expiration of short period. of time,

slmv-tc-release relay 504- also releases, and at its right armature immediately opens the previously described shunt circuit for relay 1 310 which then energizes in the locking circuit for relay 509, which circuit finds ground at the lower armature and front contact of relay 503. Energization of relay. 510 closes a circuit from grounded battery, winding of marginal transfer relay 310, back contact and left armature of relay 308, outer left armature and front contact of relay 501, right armature and front contact of relay 510, left armature and back contact of relay 515, winding of relay 507. front contact and left armature of relay 506 to gzround. .l'lclay 507 energizes and breaks the lockiim; circuit for slow-to-release rela 506 which, after an interyal oftime, releases. Relay 310, being marginal, does not energize in se ies witl'rrelay 507. Energization of relayjll? establishes'acircuit for relay 516 traceable from grounded battery, winding of relay"516, front contact and armatureof relay 507. back contact and left armature of relay 508 to ground. Relay 516 energizes ahdby attracting its armatures extends the conductors 511, 512, 513 and 514: to the junction relay 501. It will be seen by reference to the translating mechanism shown at the left of Fig. 3 that the relays, including relay 317, which are individual to the subscribers lines, are controlled by two sets of conductors, one extending through the back and the other through the front contacts of relay 310. The selection of a group of these individual relays is controlled through theback contacts of said relay by the energization of one of the translating relays, while the selection of an individual relay in the selected group is controlled through the front contact of said relay 310. It is thusobviousthat any one of the individual relays may be identified by electrically distinguishing two conductors, one each in the principal direction of a two co-ordinate system. For the purpose of illustration, let it be assumed that the tens digitof the wanted line is 1. In this case, counting relay 1 is the only relay energized and locked up and a circuit will then be established from ground at the left armature and front contact thereof, conductor 511, uppermost armature and front contact of relay 516, front contact and innermost right armature of relay 501, and winding of translating relay 311, individual to the selected outgoing link circuit, to grounded battery. Relay 311 energizes and, closes a circuit for tens relay 315, extending from grounded battery, winding of said relay, back contact and innermost left armature of relay 310, back contact and innermost armature of relay 31 1, front contact and outer left armature of relay 311, back contact and right armature of relay 312, back contact and left armature of relay 313 to ground. Only four of the tens relays including relay 315 are shown, but it is to be understood that there are ten of these relays provided, nine of which are common to a group of relays individual to a number of subscribers lines, some of said relays beingillustrated within the dotted line enclosure in Fig. 3. It is'to be understood that such relays as are shown in this dotted rectangle are individual to the connecting link circuit shown in Fig. 3. Relay 315 energizes in the circuit last, described and through its left armature and front contact applies battery to the group of individual relays including relay 317. Belay 315 looks up over acircuit extending from grounded battery, winding, right armature and front contact of said relay, winding of relay 316, back. contact and right armature of relay 318, right armature and front contact of relay 303 to ground. Relay 316 energizes and atits lower armatures breaks the incoming link circuit extending toward the called subscriberfs substation. Ground ap lied to the upper armature and front cont-act of relay 316to prepare a 509 and 510 remain energized over the previously described locking circuit for relay 509 and the entire impulse controlling mechanism is now ready'to receive the second set of impulses corresponding to the'units digit of the wanted line. I f

In response to the first impulse of th second set, relay 300 deenergizes and again closes the previously described energizing circuit for relays 504 and 505. Relay 506 again energizes and locks up to the ground at the back contact and left armature of relay 508. When relay 504: attracts its right armature, acircuit is closed for relay 515 extending from grounded battery, winding of relay 515, back contact and left armature of relay 517, front contact and left armature of relay 510, which remained energized, right armature and front contact of relay 504, front contact and lower armature of relay 503 to ground. Relay 515 energizes and locks up through the winding of relay 517, but this latter relay doesnot energize at this time, due, to the shunt circuit extending from ground at the lower armature and front contact of relay 503, front'contact and right armature of relay 504:, left armature and front contact of relay 510, left armature and back contact of relay 517, right armature and front contact of relay 515, winding of relay 517, and/back to ground at the lower armature of relay 503. Energization of relay 515 permanentlyopens, at its left armature, the circuit of relay 507, and thus prevents the same from becoming energized at the termination of r the secondset of impulses. The counting relays are again operated in accordance with the impulses transmittedin the same manner as previously described in connection with the tens impulses, and at the termination of this operation, the impulse circuit, through relays 50a and 505, is opened and these relays become deenergized. Release of relay 50 1 opens the shunt circuit for relay 517 which then energizes in, the locking circuit for relay 515. Relay 508 is then energized over a circuit extending from grounded battery, winding ofrelay 508, right armature and front contact of relay 517 to ground. A circuit is then established for relay 516 extending from grounded battery, winding of relay 516, front contact and leftarmature of relay 508 to ground. Relay 506, after the expiration of an interval of time following the removal of ground at the back contact and left armature of relay 508, becomes deenergized and opens the locking circuit for the counting relay which has remained energized, but before this occurs the relay individual to the called line is energized. The energization of relay 516 over the circuit just described for the same extends the conductors 511 to 514 to the right armatures of junction relay 501; Si-

Inultaneou'sly with the energization of relay 516, a circuit is closed for marginal relay 310, extending from grounded battery, winding of relay 310,back contact and left armature of relay 308, outer left armature and front contact of relay 501, right armature and front contact of relay-508, front contact and left armature of relay 506 to ground, this circuit having been closed before relay 506 released. Relay 310 energizes in this circuit due to the fact the same does not now pass through the resistance of relay 507 and in attracting its left armatures, said relay 310' extends the leads from the several translating relays 311 to 314 to the individual relays of the several groups. Thus, by means of relay 310, the effect of energizing one or more of the translating relays is transferred from the tens relays to the individual relays which connect the incoming link circuit to the called line. Assuming now that the units digit of the wanted line is 2,'counting relay 2 would have been energized'and locked up to ground at the frontcontact and left armature of relay 506, and previous to the deenergization of this latter relay, a circuit is closed from ground at the left armature and front contact of counting relay 2, conductor 512, next to the uppermost armature and front contact of relay 516, front contact and next to the innermost armature of relay 501, and winding 'of translating relay 312 to grounded battery. Relay 312 energizes and completes a circuit for individual relay 317 extending from grounded battery, left armature and front contact of relay 315, right winding of relay 317, front contact and next to the innermost left armature of relay 310 which has now become energized, back contact and next to the innermost armature of relay 314-1, back contact and inner left armature of re lay 311, front contact and left armature of relay 312, back contact and armature of re lay 313 to ground.

At the time that relay 310 energizes, the dial tone is disconnected and a locking circuit is closed for relay 310 extending from grounded battery, the winding, front contact and inner right armature of said relay, winding of relay 308,- front contact and upper armature of relay 316 to ground. Energization of relay 308 establishes anenergizing circuit for relay 307 extending from grounded battery. r-rinding of relay 307, front contact and right miniature of relay 308 to ground. Relay 307 looks up over the circuit extending from grounded battery, winding, front contact and inner armature of said relay, right armature and front contact or relay 303 to ground. Energization of relay 307 also breaks the circuit for relays 305, 501, 501 and 503 which circuit, as previously described, extended from grounded battery,

outer right'arniature and back contact of relay 301 through the relays mentioned to ground at the lower armature of relay The relays which were energized and locked up in this circuit now release. Relea. e of relay 503 breaks the locking circuit for relays 509, 510, 515 and 517. Release of the latter relay causes the deenergization of relay 508. Relays 50 1 and 506, having become deenergized, after a lapse of time, the entire impulse controlling mechanism is restored to normal, since the energizing circuit for any of the translating relays which had operated, is now broken, due to the release of relay 501. t is now apparent that relays 315 317 areenergized.

Let it be assumed now that the called line individual to relay 317 is idle and also. for the sake of simplicity, that the line previously described as the calling line from substation A illustrated in Fig. 1, is the called line. It is tnen to be borne in mind that the called line junction relay 201 is deenergized.

pon energization of relay 317 individual to the called line, and shown in Fig. 2, a locking circuit is established therefor extending from grounded battery, left winding, front contact and innermost left armature of relay 317 to ground at the right armature and front contact of relay 303. A circuit is also closed from grounded battery at the cutoff relay 101 of the called substation, winding ofsaid relay, innermost left armature and back contact of relay 201, innermost left armature and back contact of junction relay 203, the innermost left armatures and back contacts of all other junction relays within the particular group with which the called line is associated, right armature antL contact of relay 317, shown in Fig. V, winding of relay 313, right armatme and front contactof relay 303 to ground. Relays 101 and 318 are energized in this circuit. Energization of relay 318 breaks the previously described locking circuit for 315 which extended through the right armature and back contact of said relay 318. Relays 315 and 316 then deenergize and by causing in turn the deenergization of relays 308 and 310 restore the junction line connect ing relay selecting means to normal. Relay 318 also establishes a circuit for relay 306, extending-from grounded battery, winding of relay 306, left armature, front contact a 1rd left windingof relay 318, right armature and front contact of relay 303 to ground and relay 3 8 locks up in this circuit. Operation of relay 300 prevents the busy tone from he- New ing impressed upon the calling line. At the time that relay 316 deenergizes, a ringing current is applied to the called line extending from the ringing current generator, upper winding of relay 319, back contact and inner upper armature of relay 319, lower armature and back contact of relay 316, mindle left armature and front contact of relay 31'1", the ringer apparatus at the called substation, front contact and outer left armature ofrelay 317, back contact and inner lower armature of relay 316, outer upper armature and back contact of relay 319 to ground. Relay 319 is marginal and the resistance of the ringer apparatus at the called substation prevents this relay from becoming energized at this time. However, when the called subscriber removes his receiver from its switchhook, sufficient ringing current will pass through the upper winding of relay 319, to energize the same, and said relay, then locks up over a circuit extending from grounded battery, lower winding, lower armature and front contact of said relay, right armature and front contact of relay 306 to ground. Energization of relay 319 establishes a circuit for relay 309 extending from grounded battery, right winding of relay 309.. front contact and inner upper armature of relay 319, then over the previously described circuit through the substation, uppermost armature and frontcont-act of relay 319 and left winding of relay 309 to ground. Relay 309 supplies talking current to the called substation line and the connection now having been established, conversation between the calling and called subscribers may proceed.

At the termination of the conversation between the calling and the called subscribers, the replacing of the receiver upon its switchhook at the calling subscribers substation will release the relay 300 which in turn causes the deenergization of slow-to-release relay 303. The removal of ground from the right armature. of relay 303 breaks the locking circuit for relay 307 which then releases. The circuit for relays 306 and 318, in which the latter relay is locked, is also broken by the removal of ground from the right armature of relay 303 and said relays 306 and 318 also deenergize: Release of relay 306' removes the holding ground for relay 319 which deenergizes and at its upper armatures breaks the circuit for relay 309 which also releases. right armature of relay 303 also causes the deenergization of the cut-off relays at the calling and called subscribers substations and furthermore breaks the locking circuit for relay 317. In addition to causing the deenergization of the cut-off relay 101 at the calling subscribers substation, the release of relay 303 also breaks the locking circuit for junction relay 201 and relay 302 which re The removal of ground at the lays were energized in the circuit for said cut-off relay. r

If the wanted line had been busy as a calling line, one of the junction relays 201, 203 or similar relays individual to the several outgoing link circuits would be energized. However, upon energization of relay 310 at the termination of the selection of one of the counting relays corresponding to the units digit of the wanted line, relay 307 would be energized and at its outer armature break the circuit for relay 30f as.pre viously described. It will be recalled that in the event the called line is idle, a circuit is established for the cut-off relay of said line which extended through the inner left armatures and back contacts of the junction relays 201 and 203, right armature and front contact of the individual relay 317, the right winding of relay 318 to. ground at the right armature and front contact of relay 303. Therefore, when the wanted line is busy as a calling line. one of said junction relays being energized, the circuit just referred to through relay 31.8 which would otherwise have energized said relay is now broken and relay 318 will fail to operate. This will prevent energizatioi'i of relay 300 so that upon the release of relay 305, a busy tone is applied to the calling line from the busytone apparatus, back contact and outer armature of relay 305, back contact and inner left armature of relay 306 and right winding of relay 309 tog-round battery. This busy tone current is inducedinto the left winding of relay 309 from whence the same is transmitted to the calling line. T he calling subscriber hearing this busy tone replaces his receiver upon its switch-hook and causes the release of relay 300, with the result that all other relays which have been energized will now restore and the apparatus will be in condition. to receive another call.

If the desired line is busy as a called line, relay 318 would again fail to energize due to a short-circuit extending from ground at the. front contact and right armature cf relay 303, shown in Fig. 3. tln'ough the l -ght winding of relay 31.3, front contact and right armature of relay 317 ind 'idual to the called line, right armature front contact of relay 317, also individual to the called line, and to an incoming linkcircuit which would have been employed in calling the wanted line, to ground at the right armature and front contact of the relay 303 of another switching'apparatussuch as that shown in Fig. 3 which would have been employed in selecting said wanted line. The failure of relay 318 to operate will. again apply a busy tone to the calling line. as previously described, and soon as the calling party replaces his receiver. the apparatus is l'tSlXi-lfll to normal.

Should a calling subscriber at substation A, desire a connection to a central office exchange, the removal of the receiver at substation A will again cause the operation of a calling line junction relay, such as the relay 201 and its out-going link circuit, and also an impulse controlling mechanism such as shown in Fig. 5, in the same manner as previously described. The calling subscriber may now dial for an idle central oilice trunk. Assuming that the digit corresponding to the central oi'lice trunk is 0, the counting relay 10 will be energized and locked up, in the same manner as described in connection with the operation of the counting relays, thus applying ground to the three conductors 511, 512 and 514:. As soon as relay 516 is energized, this ground is extended through the innermost, next to the innermost and outermost armatures of relay 501, and through the windings of translating relays 311, 312 and 31 1 to grounded battery. These latter relays are energized and a circuit is then established for the relay 320 extending from grounded battery, winding of relay 320, front contact and next to the outermost armature of relay 314, front contact and inner left armature of relay 311, front'contact and right armature of relay 312, back contact-and armature of relay 313 to ground. Relay 320 energizes and applies ground at its front contact and left armature to the conductor 321. Relay 320 locks up over the circuit extending from grounded battery, winding, right armature and frontcontact of relay 320, winding of relay 316, back contact and right armature of relay 318, right armature and front contact of relay 303 to ground. Relay 316 is energized in this circuit. If all central office trunks are idle, the ground atthe left armature of relay 320 is extended over conductor 321 through the middle armature and back contact of the preselecting relay 2041, individual to the first central office trunk, and right winding of junction relay 205 to grounded battery. ltelay 205'is energized and establishes a circuit for the line relay 10 1 extending from grounded battery, right winding of relay 104:, back contact and inner lower armature of relay 105, front contact and next to the outermost left armature of relay 205, middle left armature and front contact of relay 201, subscribers substation apparatus, front contact and outer left armatureof relay 201, outermost left armatureand front contact of relay 205, upper armature and back contact of relay 105 and left winding of relay 104.- to ground. Relay 10 1 energizes and establishes a circuit for slow-to-release relay 106 extending from grounded battery,winding of relay 106, front contact and inner most :nature of relay 1041 to ground. Energization of relay 106 establishes a locking circuit for relay 205 extending from grounded battery, left winding, innermost left armature and front contact of relay 205 and left armature of relay 106 to ground. This locking circuit is established before the locking circuit for counting relay 10 is removed by the deenergization of relay 506 since the release of this counting relay deenergizes translating relays 311, 312 and 314C. Energization of relay 106 also establishes a circuit for the pro-selecting relay 20%]: extending from grounded battery, winding of relay 204 to ground at the left armature of relay 106. Relay 20a energizes and thus pre-selects the next idle central ollice trunk so that another call directed to a central oflice trunk coming in over a connecting circuit similar to that shown in Figure 3 will cause the actuation of relay 206, for instance, assuming that, as indicated, conductor 207 is associated with connecting circuit- 208. At the time relay 106 is energized, a circuit is also established for relay 301 extending from grounded battery, winding of said relay, next to the innermost left armature and front contact of relay 205 and left armature of relay 106 to ground. Relay 301 energizes and at its outer right armature breaks the circuit for relay 305 with the same results as previously described, relay 503 deenergizing and permitting the return of the impulse controlling mechanism to normal. Owing to the energization of relay 301, relays 300 and 303 also release. Deenergization of relay 303 removes the locking ground for relays 316 and 320 which then deenergize. Relay 302 which was locked up to ground at the right armature of relay 303 does not, however, release since it now finds ground through the front contact and inner right armature of relay 301, next to the innermost left armature and front contact of relay 205 and left armature of relay 106.

l l hen relay 104 is energized, as previously described, a ground is applied through. the middle and outermost armatures' of relay 10% to both sides of the trunk leading to the central office. This will cause the operation of a signal at the central office operators position in'a manner well-known in the art, and upon the insertion of a plug into the central ofiice jack, a circuit is closed through the winding of relay 110. This relay energizes and closes the circuit for relay 111 traceable from grounded battery, winding of relay 111, right armature of relay 106, front contact and armature of relay 110, to ground. Energization of relay 111 places a shunt 125 about relay 110 for talking purposes and through its inner right hand armature establishes an energizing circuit for relay 108 which in turn through its armature places a substitute ground on cuit, Energizationof relay 111 closesa circuit for relay 105i traceable from grounded battery, winding of relay 105,- outer right armature and front Contact of relay 111.v

irt'eiay 105 energizes-and extends the calling subscribers line through to the central oil-f lice operators posit-ion andalsobrealrs the circuit for line relay 10 1 which then deener gizes andin so doing, removes the holding ground for relay 106."

therefor snow transferred to the lowermost armature and front contact of relay 105, lhe calling subscriber may now coniinuni= cate with the operator at the central or'lice' ex'change who then completes the onnection between the calling; and called subscribers in well'lrnownmanner. 'l ilhen the callng subscriber replaces hisreceiver upon its switehhook at the termination or a call; a

signal will be 0 erated at the operators not. i L

sit-ion to indicate that connectionis to Removal of the plug be disestab.lished. from the central officejaclrrcauses the de energization of relay" 110 which, upon re leasing, removes the holding ground for relaylll which then releases and causes relay 105 and consequentlyrelay 106 to deenergize. Release of relay 111 also removes the holdingggnroundfor relay 108 which releases. Deenergization of relay 106 removes the i v ground from its left armature and thereby causes the release of relays 2042 205 301 and The apparatus 15 now in normal position.

On ineornin calls from thecentral oilice. one of the receiving stations indicated at the left in l5 1 is first selected and upon ascertaining from the central office operator the number oi the desired subscriber within the exchange the attendant at the selected receiving station dials for the wantedsubscriber in the same manner as described in connection with the establishment of a call between subscribers within the exchange. The receiving stations are of the same ti no i as the ordinary subscribers stations with the exception that additional junction points are providedas shown. The connection be tween this additional apparatus and the ordinary equipment is indicated by the con nectlon between the line of substation A and the first receiving station line. In establish- 1 ending! However. relay 106 does not deenergize's ince the holding-ground.

right armature e lower armature o'f'relay 117gconductoit, 1O9 5front contact and right armature of ound, Removal of the reordinary mannerj-When she does this, re-w 110 I 12061 by ringing current flow-, 1H6 through'jrelay 110 and condenser 126.

en didiiigii'oh grounded battery, winding relay 112. contactspr1ng 113e,, :tront contact energizes and locks up over acircuit e1;-v

trorn Wounded batteryp winding,

contactspring 114-: to ground.

R- layllQ at its left-handarniature' then esmatureol' relay ll0 to ground. Relay a right armature "of said" rcuit then established for relay "112 f 7 ta -fishes a condition for the selection of one i the receivine stationsshown a the left a of 1 1 ay' -115l bacl: contact and inner armature oi-rrelay 127. frontcontact'andinnerarma ture or preselecting relay 116, which is eners gized. through the busy condition of the associated receiving-station as Wllllllelelllitftfi rqopear. front contact and left armatureof relay 112 to ground. Relay 115 locks up over a circuit extending from grounded bat-v tery winding right armature and front con tact ofisaidirelay, back contact and lower armature of relay 11.7,conductor 109, from contact and right armature of relay 108 to ground and through its outermost letthand: armature closes circuit in parallel to rep nih operation orflrelay 115, a-circu'itis closed lay 12'? and cut ofi' relaylOl'.

to apply ringingcurrent' to the receiving station apparatus extending from a sourcev of ringing-p current left winding" of relay 1181 back contact and oute rlle'ttarmature of relay,- front contact and middle. left ai'n aturegof relay 115-, the receiving: station apparatus' which similar in all respects to tl1e.apparati1s of a, subscribers substa-f tion, innermost-left armature and front con: tact ofjrelay 115 inner leftgarmature and baokcontaetofrelay 118 to ground. The, running; current s appl ed to the, recei ing station line until-the attendant thereat re moves the receiver 1 from its swijtchhook 3 at y 1 Should the first receiving station be busy. a clrcult may be traced from grounded battery, winding of unction rewhich'ti'nie relay 118, one iz-es a dflloelrs upovera circuitextending rroni grounded battermought winding, i ront :conta t and relay 118; baclr contact relay 108 to; ceiver from the switchhook the receiving station also closes a 'circuit traceable from grounded l'iattery, winding of rela y;119.

baekcontact and outer armaturet 'eutotlrelay 120 uppermost armature and back contact of relay 117.; vfront contact and inner left armature of relay l ltlgtront'contact and innermost left armature of relay llfi, receiv-[ ing" station apparatus, middle left 'arinai ture and frontcontactofrelay 115 outer leftarmature and trontcontact oi? relay 118-,

, ture and back contact of relay 120 to ground.

' rtelays 121 and 119 energize in this circuit and relay 121 establishes a circult for slowto-releas'e relay 122 extendingfrom' grounded battery, winding of relay 122, front contact and armature of relay 121 to ground. Re-

lay 122 now closes a circuit through its right-hand armature and I the impedance 128 across the trunlrfor energizing line relay 10d. Relay 10 1 attracts its armatures and by closing a grounded shunt across the outgoing end of the trunk causes the energization of relay 110 andextinguishes the usual supervisory lamp at the central oflice operators position. at its innermost arma-.

ture relay 10 1 energizes relay 106. Relay 106 at its left-hand armature breaks the locking circuit for relay 112 which thereupon-retracts its armatures. Energization of relays 106 and 110 closes a circuit previously described for relay 111. Relay 111 opens the circuit for relay10'7 and at its outermost rightarmature closesa circuit for relay 105. Relay 111 at its innermost; right armature holds relay 108 energized. oil relay 10 1 and extends the trunk to the contactsof relay 117 whereby the party connected through the central oiiice may communicate with the attendant at the receiving station through the condensers 129 and 130. Relay 119 in energizing attracts its left armature, and closes a circuit for relay 123 extending" from grounded battery, winding of relay 123, front contact and left armature oi relay 119 to ground. By at tracting its right armature. relay 119 closes a circuit to select the first idle outgoing link circuit in the same manner as described in connection with the establishment of a call between subscribers within the exthis informationfthe attendant may operate the impulse sendingdevice at the re.- ceiving'station to transmit impulses corresponding to the digits of the wanted line, and thus operate the impulse controlling mechanism in the same manner as previou'sly described the impulses not-interfering with the trunk line due" to the condensers 129 and 130' and the 'slow-to-release construction of relay 122.,

Elhould the wanted line be idle. ringing current will be applied. to the line from relay 319 and uponfthe called subs riher answering. relay 309- will energize. A 0113- cuit will thenbe established which extends from grounded bat ery, upper winding of relay 117, outermost left armature and 'windingoft relay 301 armature and from The energization ofrelay 105 cuts 7 ground for relay 111.

front contact of relay 202 which became energized when line'relay 119 operated, as suniing that the first outgoing link circui the one seleced, winding 01' relay 322,

front contact and armature of relay 309 a), ground. Relay 117 becomes energized in this circuit an'd'by attracting its upper arrnatures extends the calling line over the central oilice trunlr, through the armatures of relay's202 319 and 2317 individual to the called substation. Relay 117 locks up over the circuit extending from grounded battery. windings, front contactand lower armature of relay 117 ii'ront contact and right armature of relay 108 to ground. Relay 322 isalso energized in the operating circuit of relay 11? and by attracting its armature closes a, circuit for relay 301 extending from grounded battery,

contactot relay 322, front contact and armature of relay 309 to ground. Relay 301 energizes and releases the impulse controlling mechanism, aspreriously described so that the same may again be selected. lielays 300 and 303 also become deenergized. Upon operation of relay 301. a holding ground for relay 302 is extended through the front contact and inner right armature of relay 801 armature and front contact oitrelay 322.and front contact and arnia ture of relay 309. it the time that relay mature of relay .117 is broken and relay releases. The preselecting relay-127 and the cutoff relay 101 also deenerg'ze due to the release 01"" relay 115. The locking circuit for relay 118 is also broken by the energization of relay '11? and said relay 118 together with relays .12]. and 122 release. The attendant at the selected receiving stir tion replacesthe receiver upon its switchhook and said station can now be selected "for another call Con' ersation may new proceedbetween the cal c subscriber and the called subscriber in nu the exchange and at the termination otfa conversation. the mechanism individual to the outgoing link circuit is returned to normal in the same manner previously described. ll hen relay 309 deenergizes, the'holding ground is removed for relays 117. 322., and 301 which then deenergize. At the termination of a call, the operator at the central oflicereceives the usual si nal and removes the plug from its jack and in so doing releases relay 110, which removes the holding This relay deenergizes'and removes the holding ground for slow-to-release relay 108. Relay 111 upon releasing breaks the circuit for cutofi relay 105. Relay 105 then releases and causes the 1 tionto the calling subscriber deenergization of relay 106 wh reupon the ii'iechanisin is again iii-normal position, the.

testing ground for this mechanism having been removed Upon deenefrgization of relays 108 and'lOG; I

lithe called line is busy, either as a calling or a called line, a busy tone from the apparatus BIZ in Fig. 3 will betrans ini ted, to the attendant at the selected receiv ng station in the same manner as de-f scr bed in connection "with the establishment of. a call between subscribers within the eXcl1ange,-and said. attendant upon hearing this busy tone, will inform the central OlllC-S operator of the fact that the wa ted line isbusy and will then replace'the receiver :apon'the switcbhoolr. The operator at the central exchange then gives this informatinues the connection.

1. In a telephone exchange system, calling and called subscribers lines, another line for extending said calling line, an impulse controlling mechanism including a set of counting relays, means associated with said other line for selecting said; impulse controlling mechanism, variably operable :means for actuating "said impulse controlling mechanism whereby certain of said counting relays are energized, and meansdirectlyrespon'sive to the energization of said counting relays for extending saidcalling subscribers line to'the called subscribers line.

In a telephone exchange system, calling and-called" subscribers lines, an outgoing;-

liue iorextcnding said calling line, an: lIIle pulse controlling mechanism includinga set of counting relays, means associated with said out-going; line for selectingsaid impulse controlling; mechanism, variably operable. meals for actuating said impulse controlling mechanism whereby certain of said counting relays are energized, intermediate lines to which are applied a certain electrical condition upon the energization of said counting relays, a switch individual to said, called line, andmeans directly responsive to said electrical condition on said intermediate lines for operating said switch to connect the calling to the called line.

' 3. In a telephone exchange system, calling and called subscribers lines, an outgoing line for extendln aid calling line, an nn pulse controlling mechanismincluding a set. of counting relays, means associated Wltll said outgoing line for selecting said impulseeontrollingz mechanism. variably operable means for actuating; said impulse controlling mechanism whereby certain of i said counting;

, relays energized. intermediate lines to which are applied a certain electrical condition upon the energization of said count ing relays, a switch individual to said called ing' 'elays. a switch ind and discon- 1 "controlling mechanism tor selecting'a line, and" a group of translating devices coordinat ng in'response to the electrical consaid intermediatelines for operat ing said switclito interconnect the calling and called subscribers lines.

el. In telephone exchange system, calling and called subscriberslines, an outgoing:-

line for extending said calling line, an impulse cont-rolling mechanism including a set of counting relays, means associated with said outgoing line for selecting said impulse controlling" mechanism.,, variably operable meansfor. actuating said impulse controlling mechanism whereby certain of said counting relays are energ sed, intermediate linesto which are applied a certain electrical conditionupon the euergization of said countline and clectical condition for operating said switch.

to interconnect the calling}; and called sub scribers lines.

In telephone exchange system, a plurality oi subscribers lines, outgoing and incorniiu vlines serving said subscribers lines, a switch individual to each subscrib rs line and operable to interconnect a calling with a calledsubscribers line over outgoing and incoming lines. impulse controlling mech-I anism to whichan outgoing line isextended, and a decimslly controlled. translating mech anisii. actuated by saidimpulse controlling mechanism for operating one of said switches in a non-decimal manner.

6., In. a telephone exchange system, a pluralityfl-oi' subscribers lines. outgoing and ulse controllin \llld-l to said called I plurality relays certain of which are ClLUTGClIH Qlj responsive to said of said switches, and means controlled by another operation of said impulse controlling mechanism for selecting aswitch in the selectec'l 'group. i I i ,7. in a telephone exchange syster a pinralitvoi subscribers lines outgoing-and 'incoming lines-serving said subscribers lines.

switch lndividualto each subscribers line, and operable to interconnect a calling with a called subscribers line over outgoing and incoming lin es, said switches being arranged in groups, an impulse controlling); mechanism selecting a v for actuating to which an outgoing line extended, intermediate lines associated with said impulse controlling mechanisn'i and upon which a certain electrical condition is imposed by said mechanism, translating devices responsive to said electrical condition, a group of relays one oi Wl'llCll is operatedby said translating devices in response to one operation of said impulse controlling mechanism tor group of said switches, and a relay controlled by another operation of said impulse controlling mechanism to cause another actuation or said translating devices toselect one of the switches in the selected group. l

8. In a telephone exchange system, calling and called subsc oers lines, an outgoingline tor ext-ending said calling line, an impulse controlling mechanism including a set of counting relays, means associated with said outgoing line ior selecting said impulse con trolling mechanism, variably operable means said impulse controlling mechanism whereby certain of said counting relays are energized, means directly re sponsive to the energization ot. said counting relays for extending said calling subscrib ers line to the called subscribers line, and means actuated thereupon for restoring said impulse controlling mechanism to normal.

'9. In a telephone exchange system,a pluralit of subscribers lines, outgoing and in coming lines serving said subscribers lines, a switch individual to each subscribers line and operable to interconnect a calling with a called subscribers line over outgoing and incominglines, said switches being arranged for selecting a switch in the selected group,

and means for restoring said impulse controlling mechanism to normal after each actuation thereof;

10. In a telephone exchange system,

groups of subscribers lines, outgoing and incoming lines serving said subscribers lines, means for selecting an outgoing and an in-' coming line, impulse controlling mechanisms,switching means operable to select one :01"- said impulse controlling mechanisms,

a variably operable sending device for controlling the operation of the selected impulse controlling mechanism, groups of swltches for interconnectmg calllng and called sub scribers lines, each switch being individual to one of said lines, and decimally controlled translating mechanism directly rcsponsive to said impulse controlling mechanism torselecting a group of'switches and a switch in the selected group in a non-decimal manner. I

ll. In a telephone exchange system, groups of subscribers lines, outgoing and incoming lines, means for automatically selecting an outgoing'and an incoming line,

an impulse controlling mechanism common to said outgoing lines and including counting relays, means actuated upon the selection of an outgoing line for thereupon selecting said impulse controlling mechanism, inter? mediate lines associated withsaid counting relays, means tor operating said impulse controlling mechanism to energize certain of said'counting relays whereby a certain electrical condition is imposed upon certain of said intermediate lines, a pluralityof translating devices which coordinate in accordance with said electrical condition, and meansresponsive to the resultantcoordination or said translating devices for extendigthe' selected outgoing and incominglines to one of said subscribers lines.

12. In a telephone exchange system, groups oit subscribers lines, outgoing and incoming lines serving said subscribers lines, means for automatically selecting an outgoing and an incoming line, an impulse controlling mechanism common to said outgoing lines and including counting relays, means actuated upon the selection of an outgoing line forthereupon selecting said impulsecontrolling mechanism, a variably operable impulse sending device for actuating one of said counting relays in response to each set of impulses transmitted, intermediate lines associated with said counting relays and upon certain of which are imposed an electrical condition by the actuation of said counting relays, aplurality of translating deviceswhich coordinate in accordance with said electrical condition at the termination of the translation of each set of impulses, a group ofswitchcs selected by said translating devices in response to one set of impulses, and means for causing said translating devices to select a switch in said group atthe termination of another set of impulses.

18. In a telephone exchange system, alplurality of subscribers lines, outgoing lines common to said subscribers lines, means for connecting one of said subscribers lines to an outgoing line, a. plurality of trunks, an impulse controlling mechanism to which said outgoing line is extended and including a set of counting relays, means directively re sponsive to the operationof one of said c0untingrelays for extending said outgoing line to the subscribers line to said operators posi-' 'tion.

outgoing lines-common to said subscribers and attendantslineman operators position, means for preselecting one of said attend ants lines, means torconnecting the preselected attendants line to an out-going line, an impulse controlling mechanism to which said attendants line isje:-:tended,ineans'directively responsive to said impulse controlling mechanism ior connecting said attendantsline to one of said SUlOSCllbGlS" lines,

and" means operated thereupon for disconnecting said attendants line'and connecting 15. In a telephone exchange system, a pinrality of subscribers lines, attendants lines, outgoing lines common to said subscribers and attendants lines, an operators position,

- means for pre-selecting one of said attendants lines, means torconnecting the preselected attendants line to an outgoing line,

an impulse controlling mechanism to which said attendants line is extended and including a set of counting relays, intermediate lines upon whicha certain electrical condition is imposed when said counting relays are operated, means directively responsive to said electrical condition for connecting said attendants line to one of said subscribers lines, and means operated thereupon for disconnecting said attendants line and connecting the subscribers line to said operators position. v

16. In a telephone exchange system, a plurality of lines, a. link circuit, groups of switches, a switch in each group being individual to one of'said lines and operable to connect the same to said link circuit, means for operating said switches including two sets of conductors, each set being in the principal direction of a two co-ordinate system,

a pluralityot translating devices associated with said conductors, and means for control ling. said devices to select a group of said switches through one set of conductorsand a switch in the selected group through the other set of conductors.

17. In a telephone exchange system, a plurality of lines, a link circuit, groups of switches, aswitch in'each groupbeing individual to one of said lines and operable to connect the same to said link circuit, means for operating said switches including twov sets of conductors, each set being in the principal direction of a two coordinate system, a plurality of translating devices associated with said conductors, and subscriber controlled means for controlling said devices to select a group of said switches through one set of conductors and a switch frality of lines, inn:

connect the same to said 7 in the selected 'calledsubsc'ribers lines, permanently paired Vmea'ns comprising individually operable ing line.

of conductors. '18. in a telephone exchang in the selec ed group through the other'set tches, a switch in eacl on idual to one of said h PllilClPill direction of a two co-ordinate system, a plurality of translating devices as I sociated with said conductors, and a plu-' rality of counting relays for controlling said devices to select a group of said switches through one set of conductors and a switch group through the other set of conductors. 1

19. In a telephone system, subscribers lines, permanently paired link circuits, subscriber controlled switching means compris ing individually operable contacts for connecting said lines to said link circuits, and means "for connecting said link circuits in pairs to torm loop circuits whereby any line may be'connected to any other line through a loop circuit. 7

20. In a telephone system, subscribers lines, permanently paired link circuits, subscriber controlled switching means compris- I, ing individually operable contacts for connecting said lines to said link circuits, means responsive to the connection of a line to a link circuit to prevent the operation olf other switching means for said link circuit to prevent double connections, andim eans' for connecting said link circuits in pairs to 'torm loop circuitswhereby any line may be connected to any other line through a loop circuit. l

21.111, a telephone system, calling and link circuits, subscriber controlled switching contacts for connecting said lines to said link circults, means for connecting said link circuits in pairs totorni loop circuits wherebyany calling line maybe connected to any called line through a loop circuit, and other switchingmeansin the loop circuit which disconnects a calling'line when applying ringing current to a called line to prevent the application of'said current to the call- 22. In a telephone system, subscribers lines, permanently paired link vcircuits, means tor joining said link circuits to form a loop circuit; whereby any line may be connected to any other line through said loop circuit, non-numerical switches through which said subscribers lines are multipled to said loop circuit, and numerical switches controlled from said subscriberslines' and through which said lines are also multipled to said loop circuit.

23.111 11 telephone system, subscribers lines permanently paired link circuits, switching means comprising individually operable contacts for connecting each line to each link circuit, means for connecting said link circuits in pairs to iorin loop circuits whereby any line may be connected to any other line through a loop circuit, :1

trunk circuit, and means controlled by said switching means and i'esponsiYe to dialing 10 impulses to extenda subscribers line to said trunk circuit.

In Witness whereof, I hereunto subscribe my name this 19th day of April, A. D. 1919.

Sim/1cm B. WILLIAMS, 31s 

